The present invention relates to improvements in separable attachments between installed and removable components of dental prostheses. More particularly, the invention relates to improvements in so-called spring-loaded retention elements of the type wherein the female detent element is normally positioned below the survey line and the male detent element can snap into the female detent element by spring action. The invention also relates to a method of making the attachment and to improvements in means for facilitating the practice of the method.
In presently known attachments of the above outlined character, the male detent member comprises a flexible or bendable spring which is receivable in the recess of the female detent member (also known simply as female). The flattest conventional male detent member uses a spring which is made of wire having a diameter of 0.7 mm or thereabout, and such wire is inserted into a compartment with certain freedom of movement for penetration into or expulsion from the recess of the female detent member. The overall thickness of the male detent member including the receptacle for the spring is in the range of 2 mm.
Certain other presently known attachments of the above outlined character comprise male detent members wherein a plunger is reciprocable under the action of a coil spring so that its head can penetrate into the recess of the female detent member. The minimum diameter of the plunger is 2.9 mm and the overall thickness of the male detent member is well in excess of the diameter of the plunger since the latter must be received, with a certain amount of play, in a suitable cylinder which is installed in the detachable or in the permanently installed component of the prosthesis. However, the overall dimensions of male detent members which employ reciprocable plungers are smaller than those of the male detent members employing the aforementioned bendable spring because the bendable spring occupies more room than the plunger and the coil spring therefor. Moreover, the bendable spring must be adequately anchored in the corresponding component of the prosthesis. Attempts to reduce the overall dimensions of male detent members which employ bendable springs have failed because a very small spring cannot be properly manipulated by the dental technician and also because the time which is required for proper installation of a very small spring would render the cost of the prosthesis employing two or more male detent members with miniature springs prohibitively high.